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Topic: Drill Doctor (Read 10715 times)

A Partridge in a Pear Tree? Or specsavers for Rob or Drill doctor for Aplletree?

Anyway more testing:

3,2 mm pop rivet drill (IXCY or something...) really nice drills I buy them 10/20 pcs boxes...helix about 26 degrees, pint angle about 118. Align it on -1 mark, sharpen and split. Unbelievably perfect. See the picture. It did drill well and in size (that I could measure).

Then with great trepidation I choose Alpen Forte 6,5 mm slow helix 35 degree model that had served well but had one edge chipped. Align it to -1 notch and sharppening looked about right. No need to split, original split was close. Drilled well.

I thought that I have now it pretty much sorted and choose old traditional form English made Dormer 10,0 mm drill that had corners chipped. It has been sharpened by shop at one point. Chissel angle was about 60 degrees, point angle about 116 degrees and helsix close to 30 degrees, nothing exotic.

Aligned it exactly at 118 degree mark, sharpening took ages close to 30 rounds, but looked pretty much ok in the end. Chissel angle close to 45 degrees. Splitting just about touched it. But the drill worked fine. But probably would not be big tamale on startting the hole.

Starting to think: Does anybody knows what angle the drill lip should be set at the chuck vs. helix? Starting to think that optical setting could be more likely to hit the spot?

Happy to see you are now getting better results. I had a look at some drills I sharpened with the DD some months ago and none of them looked anything like as rough as your first ones.

I also have some 4's5's and 6mm drills which all sharpened well and cut nicely after the DD treatment.

I did also try the optical alignment method with some drills that the geometry looked wrong on after using the DD setting mechanism. It was reasonably successful,so perhaps worth you doing a bit of experimentation with that method......OZ.

How did you made the optical alignment? What was reference on the chuck and did you determined the relationship with helix angle too?

How did you set the lengt? With long drills it would be easy to make a disc w/ lock that is locked at the end of the drill in the chuck when DD aligment port is used, but here only to set the lengt (that disc as a stop) and dril/disc free to rotate until chuck is tightened.

Pekka, I didn't use anything scientific at all. I simply set the drill in the collet with the standard claw mechanism and then withdrew the collet and slightly rotated the drill while trying my best not to move it lengthwise.

I did this on some drills because it seemed the grinding op was producing a negative helix geometry at the tip of the drill. I never really fully understood why a few drills required this,but it seemed the relationship of where grinding commenced was all wrong.

The point I'm making here is that I managed to achieve an improved result by adjusting the drill by eye then you might find some further improvement by employing a setting device or using a more reliable indexing method than I used.

Thinking about the possible cause for this I think maybe some of the drills had a steeper helix angle therefore the relationship of the setting claws and the lips was wrong to get the correct grinding geometry....OZ.

My working hypothesis is that the drill helix agle and or tip geometry has effect n centering on the DD depth/claw adjustment.

Reason is the the traditional tip drills works reasonably well, but the drills with very different helix angle or exotic tips sharpen badly on first try. Then you need to check the chissel angle (DD use clock metaphore instead of angle) and adjust the initial setting for few notched either direction accordngly. It is in the manual, but I'm having problem understanding it. I think it has been simplified to a larger audience.

DD method is not bad it should work very well with standards drills and improve the sucess rate if you are very new to sharppening of the drills. It must be cheap or we would not buy it. Looks like next real step up is about 1000 EUR/USD/GBP and often it just buys speed and durability, not much more flexibility.

Now, my rationel is that if I could have an optical method of intial setting for depth and angle first time success rate should be better with DD.

Have to think of it a little.

1) My first instict was as described in the previous post to use DD setting for cutting depth and aproximate lip angle adjustment, tighten a disc/collet something to lock the depth in relation of the chuck, but allow angular adjustment and then use different fixture for optical angle adjustment.

2) Second idea was to use two V:s or something to support DD chuck and then have a plastic transparent endstop and simple craticule. Drill point is gently placed on the stop for depth and vieved from the front parallel to lines (perimeter of the craticule matked few common settings and can be turned to set desired angle), but there would be some wear. Maybe a easy to change transparent stop piece?

1) My first instict was as described in the previous post to use DD setting for cutting depth and aproximate lip angle adjustment, tighten a disc/collet something to lock the depth in relation of the chuck, but allow angular adjustment and then use different fixture for optical angle adjustment.

2) Second idea was to use two V:s or something to support DD chuck and then have a plastic transparent endstop and simple craticule. Drill point is gently placed on the stop for depth and vieved from the front parallel to lines (perimeter of the craticule matked few common settings and can be turned to set desired angle), but there would be some wear. Maybe a easy to change transparent stop piece?

Yes,that is the problem explained nicely. An optical or mechanical jig or mechanism that preserves the length setting while allowing angular adjustment would likely produce far better overall sharpening results......OZ

One of the greatest shortcomings with a device like the Drill Doctor is the very small diameter of the grinding wheel. With a wheel of far greater diameter I reckon the quality of the results would be far less hit and miss...OZ

having looked at the set up I am sure you're right. The only adjustment you have is length of splitting by retracting or extending the adjuster that determines the amount of drill ( length extended ). I will try some scrap drills when next using the DD and see what a difference retarding or advancing the holder on the drill either side of the 118 mark when setting up has on point splitting.

I tested today three drills, all same diameter one with slower helix and two with faster helix. Experiment conforms that helix angle has an effect on initial setup and shows dramatically on splitting the point.

I'm fighting the flu big time, I did not check yet what diameter they drill. I think that sharpening has failed if diameter is 0,1 mm larger than the drill at lips.